Electron discharge device of the cavity resonator type



E. osTAs jan'g z'i; 1948.

ELECTRON DISCHARGE DEVICE OF THE CAVITY RESONATOR TYPE Filed June 3, 1943 2 Sheets-$heet 1 Jan. 27,1948. Ros A 2,434,962

ELECTRON DISCHARGE DEVICE OF THE CAVITY RESONATOR TYPE Filed June 5, 1943 2 Sheets-Sheet 2 IN VEN TOR. 519N557 #087746 AGEVT Patented J an. 27, 1948 ELECTRON DISCHARGE DEVICE OF THE CAVITY RESONATOR TYPE Ernest Rostas, Lyon, France, a'ssignor to International Standard Electric Corpor'atiom'New York, N. Y., a corporation of Delaware Application June 3, 1943, Serial No. 489,473 In France May '17, 1940 Section 1, Public Law 690, August 8, 1946 Patent expires May 17, 1960 7 Claims. (01. 250-275) The present invention relates to electron discharge devices and more particularly to designs for those devices of this kind that use modulation of the velocity of the electrons.

According to certain of its characteristic features the present invention provides for velocity modulation devices of concentric design comprising at least one resonant cavity having axial symmetry of revolution and being permeable to the electrons and coaxial to the emission cathode, so that the entire beam of electrons passes perpendicularly to the axis of revolution of the cavity. When use is made of a single cavity resonator in a concentric structure of this kind, a coaxial electrode for reflecting the electrons is provided around the said cavity resonator. When use is made of two cavity type resonators in the path of the beam, the electrode that surrounds the outer cavity is simply an electron collector.

Among other advantages, concentric electrode structures of this kind have that of reducing the current density of the beam for the same transported current with respect to the units in which the electronic flow is concentrated in an elongated beam projected along a path, and also that of making it easier to obtain a beam suited to the design, since the concentration of a flow of electrons between two planes is easier to efiect than that of a flow of electrons in pencil form.

Fig. 1 shows in elevation, and partly in section one example of a type of construction that embodies characteristic features of the invention;

Fig. 2 is a sectional view taken along 2-2 of Fig. 1;

Fig. 3 is a section on a larger scale taken along 3-3 of Fig. 1; and

Fig. 4 illustrates a modified portion of the unit shown in Fig. 1.

The devices shown in Fig. 1 comprises within an evacuated envelope I, e. g. of glass, a cathode 2 of elongated cylindrical shape, a cylindrical electrode 3 coaxial with cathode 2 and serving to reflect or return the electrons emitted by cathode 2 that reach its vicinity, and an electrode 4 that is permeable to the electrons and is disposed between cathode 2 and the reflecting electrode 3 and coaxially with these electrodes.

The entire unit is supported from a reentrant stem 5 of the insulating envelope I by means of supporting rods 6, three in the example shown, as can be seen in Fig. 2. These supporting rods are carried by the reentrant stem 5 by means of collars l which may be in several parts, e. g. three, and which are secured on the stem 5, by bolts as shown at 8 that connect these parts to each other. Current orpotential lead-in connections 9 to the various electrodes pass through the stem 5, and are sealed hermetically therein.

The supporting rods 6 are secured to a circular metallic plate II! which they traverse in the manner shown at It and their upper ends pass through openings [2 in another metallic plate 13 in such a way as to center this plate 13 without being secured to it., Each of the metallic plates Ill and I3 has a diameter almost equal to that of the envelope and carries stops or short upturned rods M which thus maintain two insulating sheets I5 and IE, e. g. of mica, spaced from the metallic plates l0 and i3 that support them. These mica sheets may have the shape shown in Fig. 2. On the one hand they insure centering of the cathode 2 and, on the other hand, they serve, as shown at IT, for supporting the conductive uprights I8 on which the reflecting electrode 3 is soldered.

Cathode 2 is shown as an indirect heated cathode with only a, central portion l9 coated with electron emitting material. This active portion l9 cooperates with the permeable electrode 4. As shown in the drawing, this permeable electrode consists of two coaxial metallic sleeves 23-24 and 25-26 maintained in spaced relation by conductive spacing members 2l-28 in such away as to form an annular cavity resonator, the walls of which are completed as regards the active'portion l9 of cathode 2 by a grid that consists oftwo spaced layers of wires or rods 20 and 2| which are curved toward the outside of the unit and are set in notches in the walls of the cavity resonator like those shown at 22 in Fig. 3. This electrode unit 4 is secured coaxially with cathode 2 on the metallic plates l0 and I3.

In the operation of the above described type of construction, the electrode with a resonant annular cavity is brought to a positive potential with respect to cathode 2, and the reflecting plate 3 is brought to a negative potential with respect to that of the electrode 4 and to substantially the same or a negative potential with respect to that of cathode 2, so that the flow of electrons coming. from the emissive portion 19 of the cathode passes through the permeable electrode 4 on its way to electrode 3 and, during its passage through the annular resonant cavity, it undergoes a grouping in velocity that insures a modulation in velocity of the beam while it is on .its way to electrode 3 and returns to electrode 4 after reflection. On its passage back to electrode 4 it yields a part of its energy to the cavity resonator. This kind of operation is well known and nected to one of the walls of the cavity resonatorand that passes through a seal 3| in the insulat ing envelope I.

As mentioned, the portion 'of each wire 29 or 30 that is within thefehvelope may be flexible in order to permit free expansion of the complete unit during operation."

Fig. 4 illustrates a structurewithlfconcentric elements of the above described type but in which the cavity resonator is double, the-beam not be ing returned but being picked up by electrode 3* which is then brought to a positive-potentialwith. respect to cathode I and electrode 4. -In this case, this latter electrode consists of two adjoining cavity type resonators 32 and 33. Th'e grid portions of these cavities may be constructed in the manner described for Fig. 1, i. e. they may consist of rods bent outwardly, such as 34 and 35, which are set in notchesof coaxial cylindrical sleeves-36,31 and 33, the sleeve 31 having. two paralleliannular rims 39 which define a toroidal space-in which those electronscan freely move which have-undergone a' grouping in velocity-on their passage through grids 35 and are on their way to grids 36. i From the beam modulated in this way that passes through them, 'the grids'33 draw energy in a manner-likewise known'in devices' with'lmodulation of the yelocity of the electrons.

It can? be seen that a c'oncentr'ic arrangement of the electrodes of a velocity modulation device is more. suitable than other plane structures for obtaining a beam of electrons that cantpass through the permeable portions of an oscillatory circuitwithout being picked up'by the walls as a result of the reduced density or the beamlfor the same "transported electron current.

Although the invention" has" been described for the 'case'of certain special'example of embodiment, it is evident that it is" by no means limited theretoybut" is on "the contrary capable of nu merous modifications 'andadaptations without de arting rrcmthe scopelthe'r'eof;

What is claimedis: r

1. An ultra high frequency electron vel'ocity modulation device'i ncludin'g an electron-emitting cathddedordeveloping radial. streams of electrons; means formodulating the velocity 1 of the electrons in the path of said stream and. transferringenergy' therefrom? to an oscillating field,

the last-mentionedmeans comprising a substantiall'y cylindrical cavity: resonator' having two spaced walls concentrically surrounding said cathode, aligned windows in each "of said walls for defining said path of the streamias an annular electron path for the electrons from said cathode, electron repeller means surrounding said aligned windows, and grid electrodes mountedin each of said aligned windows, each of said" grid electrodes being, bowedoutwardly along said path ofthe electron stream from the cathode thereby defining a substantially toroidal-space between said grids.

2'. An ultra high frequency electron velocity modulation discharge device including an electron-emitting cathode fondeveloping a radial stream of electrons, a first cylindrical cavity res onator surrounding 'and concentric'with said cathode; a second cylindrical cavity 'resonator surrounding "and concentric with the "saidfirst cavity resonator, a pair of grids attached respectively to radially aligned windows in the walls of said first resonator for controlling the velocity modulation-- of electron streams therebetween, each of said grids being bowed outwardly along the path of the electron stream from the cathode thereby defining a substantially toroidal space extending acrosssaid path of the electron stream; a second-pair of grids attached respectively to radially aligned windows in said second resonator' thereby defining a second substantially toroidal spacein radial alignment with the firstmentioned toroidal space, and a common electrorr velocityl'control electrode surrounding and in radial spaced relation to said second resonator and in substantial alignment with said grids.

3. Anultrahigh frequency electron velocity modulation discharge device according to claim 2, wherein said first and second resonators are separated by a common intervening conductive wall member, the outermostgrid of the said first pair of grids defining with the innermost grid of the said second pair:of grids alocalized electron transmission chamber between the two cavity resonators which chamber extends through said common-wall and is electrically connected there with.

4. Annltra high frequency electron velocity modulat on device comprising an electron-emitting cathode for developing a radial electron stream, a cavity resonator including two cylindrical spaced walls surrounding and concentric with said cathode, each of said walls having aligned windows in which are located annular grid structures, each grid being bowed outwardly with: respect to the path of the electron stream from the: cathode thereby defining a substantially toroidal electron chamber between the grids, and ana'electron'repeller electrode surrounding said grids in spaced relation thereto and in substantial alignment therewith.

5. A device according to claim 4 in wh ch said grids are located substantially at the central portion'of said cylindrical walls, andsaid repeller electrode is mounted in substantial alignment with said central portion, and lead-in means is connected to said repeller electrode for applying thereto an electron repelling potential.

6. A device according to claim 4 in which each of said-grids comprises a series of rod-like elements extending along the length of the cathode and with the ends of the rods fastened to the said cylindrical walls at the margins of the respective window therein.

7. An ultra high frequency electron velocity modulation tube comprising a'centralgelongated substantially linear cathode member having its middle peripheral region provided with an electron-emissive coating, a first cylindrical member surrounding said cathode, a. second cylindrical member surrounding the first cylindrical memher and constituting therewith a cavity resonator, each of saidcylindrical membershaving the midi the peripheral section thereof. provided with a gridded window which windows are in substantial alignmentwith the said coated area of the cathode, and with the grid members bowed outwardly in the direction of the electron trajectories from said cathode, another .(ylindrical electrode surrounding the outer one of saidlcylindrical members in spaced relation thereto and in substantial alignment with said. gridded windcw's; and means supporting all said electrodes in fixed concentric relation including upper. and

6 Name Date Hansen et a1. Oct. 21, 1941 .Dallenbach Aug. 30, 1938 Dallenbach Aug. 30. 1938 Black Dec. 29, 1942 Litton Oct. 13, 1942 Litton Jul 14, 1942 Varian et a1. June 30, 1942 Dallenbach Aug. 30, 1938 Hansen eta] Jan. 13, 1942 

